Process for refining hydrocarbon oils



Patented Jan. 3, i950 PROCESS FOR REFINING HYDROCARBON OILS Gerrit Hendrik Reman, Amsterdam, Netherlands, assignor to Shell Development Company, San Francisco, Calif., a corporation of Delaware No Drawing. Application June 9, 1947,

Serial No. 753,579

In the Netherlands June 20, 1946 6 Claims.

This invention relates to the art of treating hydrocarbon oils. It pertains more particularly to a process for removing undesirable substances such as ash-forming constituents and/or asphaltic substances from hydrocarbon oils, especially oils of the character of mineral lubricating oils and residual hydrocarbon oils for use as fuel for, e. g., gas turbine installations.

The use of residual hydrocarbon oils, either alone or mixed with, for example, oil distillates, as fuel for, e. g. gas turbineinstallations, is attractive for economical reasons. The ash-forming constituents, however, and to a smaller degree also the asphaltic substances, generally occurring in residual hydrocarbon oils, constitute a drawback to the use of the latter as fuel oil for this purpose. The ash-forming constituents which, it will be understood, are inorganic-containing substances and form non-volatile mineral or inorganic compounds upon combustion, have a fouling effect on the installations in which said oils are used. As a result,'the installation soon begins to operate less smoothly and too soon for economical reasons the operation must be stopped for a thorough cleaning of the installation.

The asphaltic substances have the drawback in such fuel oil that they greatly increase the viscosity of the oil, so that in general it is necessary to dilute the oil with a considerable proportion of less viscous and more expensive distillate materials.

It has already been proposed to refine oils, particularly mineral lubricating oils, containing asphal'tic substances with certain combinations of extraction agents which bring about the removal by extraction of the asphaltic substances, for example, with the combination propane-phenol (and/or cresol) or with the aid of a combination such as antimony trichloride-ethyl ether, or even with a solvent extraction proportion of liquefied antimony trichloride. Application of solvent extraction forthe removal of asphaltic substances from residual oils in the production of cheap fuels is too expensive to be considered. Furthermore, even the application of solvent extraction with liquefied antimony trichloride to the refining of more valuable lubricating oils is not entirely satisfactory, particularly from the standpoint of economy. 7

It is a principal object, therefore, of this invention to provide an improved process for treating heavier hydrocarbon oils. A further object is to provide aprocess wherein asphaltic substances are more economically removed from hydrocarbon oils. Another object is to provide a process for readily, economically and effectively removing ash-forming constituents and/or asphaltic substances from heavier hydrocarbon oils, such as residual hydrocarbon oils. Still another object is to provide an improved process for the removal of asphaltic substances from mineral lubricating oils. These objects will be more clearly understood and other objects will be evident from the detailed description of the invention.

Now, in accordance with the present invention, it has been found that the above and other objects may be realized by a process wherein a heavier hydrocarbon oil which contains undesirable impurities such as ash-forming constituents and/or asphaltic substances is treated with a minor but effective precipitating and/or coagulating amount of a precipitating and/0r coagulating agent for said impurities followed by separation of the resulting precipitated or coagulated matter'together with said agent. In some cases, this treament may be combined with other subsequent treatments to provide advantageous combination treatments or processes wherein the above described treatment is in the nature of a pretreatment.

Generally described, the present invention provides an improved process for refining hydrocarbon oils, particularly residual hydrocarbon oils which contain ash-forming constituents and asphaltic substances and hydrocarbon lubricating oils which contain asphaltic substances, which process comprises treating the impurity-containing oil with an added, small amount of one or more of an agent from the halides, oxyhalides and sulfohalides of antimony, arsenic and phosphorus, which agent does not react with the hydrocarbon oil under the conditions of the treatment, there- 'by precipitating the ash-forming constituents and/or the asphaltic substances, and separating the precipitated impurities from the hydrocarbon oil. With the application of this treatment to a hydrocarbon lubricating oil fraction, the separated oil fraction may be advantageously further treated as by a solvent extraction process with a selective solvent such as a phenol, furfural, liquid sulfur dioxide, liquefied antimony trichloride, a sulfolane, etc. In that case, the combination of the first or pretreatment operation with the subsequent refining treatment as by solvent extraction materially decreases the amount of selective solvent required in the solvent extraction to an extent that there are realized economies in the overall process over the required solvent extraction when that is used alone without the advantages of the described pretreatment. Thus, when ficient antimony trichloride is utilized alone in the extraction operation to produce an oil railinate of similar quality.

In some applications of the present invention such as to residual hydrocarbon oils, such a small quantity of the treating agent may be used as will suflice to practically completely precipitate the ash-forming constituents, but to leave a part of the asphaltic substances dissolved in the oil.

Examples of substances which maiy-beusedin accordance with the invention as the treating agent are antimony trichloride, arsenic trichlm ride, arsenic tribromide, phosphorus trichloride, phosphorus sulfochloride, antimony pentach10- ride, antimony oxychloride, etc.

The quantity by weight in which the-treating agents of the invention are added to the hydrocarbon oil depends on, the quantities of ashforming constituents and asphaltic substances oc. curring in the oil to be purified. amounts of not more than about l% by weight of' the oil .to be thus treated, and in many cases not more than by weight of the oil, efiect the required precipitationiof the impurities and refinement of the oil.

The precipitation and/or coagulation treat.- ment is not confined to any particular temperature or narrow temperature range. Normal or elevated temperatures may be applied. When applying normal or slightly. elevated temperatures the precipitated ash forming constituents and/or asphaltic substances generally'do not settleout readily in the case of relatively viscous oils but may be easily separated from the oil by centrifugation. If, on theother hand, the precipitation is effected at a temperature of from about 150 C. to 250 0., the precipitates obtained will settle fairly quickly and the oil can be easily separated therefrom-by decantation.

After removal of the precipitated ash-forming constituents and asphaltic-suhstances the treating agent used for this purpose may be recovered from the oil by distillation or by shaking the oil with a solvent for the agent, which solvent is at least partially immiscible with the oil. The sep: arated solvent solution of the agent may then be separated. by distillation and any of the solvent dissolved in theoil may be separated therefrom by distillation.

When the halides, oxyhalides and sulfohalides of antimony, arsenic and phosphorus'are entrained to any considerable extent by the precipitate separating from the oil, it is in many cases profitable to recover these agents also from the precipitate. This may, for example, be effected by distillation under reduced pressure, or the precipitate may be treated with an inert diluent, such as naphtha and/or with a solvent for the agent such as a concentrated aqueous solution of hydrogen chloride, etc.. e

' In the event the foregoing described treatment 'to precipitate impurities is applied to a lubrireating oilfraction such as a hydrocarbon distillate; the thus p etreated oil may in some case be subjected to a solvent extraction treatment with g a. solvent amount of the same agent, for example, when the agentis antimony chloride. In that event the a ent remaining in the l after the first or pretreatment need not b recover d therefromv prior to the solvent extraction. Even V In general,

when the precipitating agent and the selective solvent are not the same, it often is not necessary to remove the precipitating agent remaining in the oil before effecting the solvent extraction unless the solvent is reactive with said agent, which, in general, is not so. In some cases where the agent and solvent are different the small amount of agent dissolved in the oil enhances the selectivity of the solvent toward the various types of hydrocarbons present in the 011.

After the extraction proper has been carried out, both the raflinate phase and the extract phase are liberated of the added substance (solvent) or substances (solvent and agent). It will generally be deemed desirable to recover the solvent and agent separately for the treatment of a fresh quantity of oil. The most suitable meth- To a ol n residue; 1. e. a r idue fr m Venezuelan oil, there was added 3% by weight of SbCh at 200 C. and. the mass was kept at this temperature for half an hour. The oil, formin e pp r l r, w then de nted fr m he pie oipitate which had formed and s t ede SbCIa w covered fro theoil'by first dilu ing h l tt r wi h benz neand then shakin it o t with a hydrochloric. acid s lution. The two liqu d layers thus formed were separat d and he h n zene was distilled off fromthe oil layer. As a re sult of the treatment the ashecontent of the Colon residue was lower d fromv a value of 1 6% by weight to a valueless than 0.01% by weight; the asphaltene content was lowered from 85% by weight to a value of only 0.5% by weigh Practically the same results were obtained by reating another sample of thesame res du with y weight of AsB -s instead of an equal quan ity o 510013, the other conditions. ope ati ns, tc.

being the same.

E tdmple II AVenezuelan oil residue-obtained by distilling ff from a Venezu lan crude oilthe constituents boiling above about-380 C. (atmospheric pres, sure) and which residue had an asphaltene content of 8.8% by weight, wasthoroughly mixed at .20. C. with 3% byweight of antimony ri. chloride and then was allowed to stand for half an. our. h oil was, separated fr m the e ment obtained by de entation, t s ill conta n d 0.5% by weigh of a p e te es and was subse quently xtra ted in ooun s ourrent with 40% by volum o liquefi d ant mony tr ohloride at C. n: pparatus. rovided. vw tl-ithis-1e mix ineand settl ne tenks. The. reffinete phase, aft r b ng freed fr mantimony tr chlorid c n-- sisted of an oil with a ViSCOSity-Esg 17.51, a viso s t d of 97 ands Ce redsonw r on fleme of 0.75.

W thout applyin a pretreatment as described above, a similar resultwith a. oo lntercurrent extraction in the same apparatus and under the same onditi ns waso tainede y-when the es? traction had been effected with about 75% by volume of antimony trichloride.

Thus, the combination process represented an economy of 35 volumes of SbC13 extractive solvent out of '75 volumes, for a pretreatment outlay of only three volumes of SbCls.

Thus, it is seen that the present invention provides an improved process for the removal of ash-forming constituents and/or asphaltic substances from hydrocarbon oils. The invention is of particular utility in refining residual hydrocarbon oils so that they may be used advantageously, alone or in mixtures with a content of at least 50% by weight of such residual oils, the rest being made up of, for instance, mineral oil distillates, synthetically prepared ash-free types of oil, benzene, etc., as fuel for operating gas turbine installations. Furthermore, the embodiment of the invention wherein a pretreatment as described herein is combined with a subsequent solvent extraction operation has utility as a process of greater economy for the refining and production of lubricating oils.

I claim as my invention:

1. In a process for the refinement of mineral lubricating oils which contain impurities of the character of asphaltic substances, wherein the mineral oils are subjected to solvent extraction with a selective solvent for various hydrocarbons present therein, the improvement which comprises preceding said solvent extraction by treating said mineral oil containing the asphaltic substances with a minor but asphalt-precipitating amount up to about by weight of antimony trichloride as sole active precipitating agent under conditions to precipitate at least a substantial portion of said impurities, and separating the resulting precipitated impurities from the oil prior to the solvent extraction operation.

2. In a process for the refinement of mineral lubricating oils which contain impurities of the character of asphaltic substances, wherein the mineral oils are subjected to solvent extraction with liquefied antimony trichloride as a selective solvent for various hydrocarbons present therein, the improvement which comprises preceding said solvent extraction by treating said mineral oil containing the asphaltic substances with a minor but asphalt-precipitating amount up to about 10% by weight of antimony trichloride as sole active precipitating agent at a temperature of from about 150 C. to about 250 0., thereby precipitating at least a substantial portion of said impurities, and separating the resulting precipitated impurities from the oil prior to the solvent extraction operation.

3. In a process for the refinement of mineral oils which contain asphaltic substances, wherein the mineral oils are subjected to solvent extraction with a selective solvent for various hydrocarbons present therein, the improvement which comprises preceding said solvent extraction by treating said mineral oil containing the asphaltic substances with a minor but asphalt precipitating amount not more than about 10% by weight of a halide agent selected from the group consisting of the trihalides of antimony, arsenic 6 and phosphorus and mixtures thereof, as the sole active precipitating agent, under conditions to precipitate at least a substantial portion of said asphalt substances, and separating the resulting precipitated asphaltic substances from the oil prior to the solvent extraction operation.

4. A process for removing ash-forming impurities from residual hydrocarbon fuel oils, which process comprises treating said impurity containing fuel oils with a minor but impurityprecipitating amount not more than about 10% by weight of a halide agent selected from the group consisting of the trihalides of antimony, arsenic and phosphorus and mixtures thereof, as the active impurity-precipitating agent, under conditions of temperature, time and proportions to precipitate a substantial portion of said ashforming constituents, and separating the resulting precipitated impurities from an improved fuel oil.

5. A process for removing ash-forming impurities from residual hydrocarbon fuel oils containing also asphaltic substances, which process comprises treating said impurity-containing fuel oils with a minor but impurity-precipitating amount not more than about 10% by weight of a halide agent selected from the group consisting of the trihalides of antimony, arsenic and phosphorus and mixtures thereof, as the active impurity-precipitating agent, at a temperature up to about 250 C., and with proportions selected to selectively precipitate substantially completely said ash-forming impurities while leaving a substantial portion of the asphaltic substances dissolved in said oil, and separating the resulting precipitated impurities from an improved fuel oil.

6. A process for removing ash-forming impurities from residual hydrocarbon fuel oils containing also asphaltic substances, which process comprises treating said impurity-containing fuel oils with a minor but impurity-precipitatin amount not more than about 10% by weight of antimony trichloride, as the active impurity-precipitating agent, at a temperature up to about 250 C., and with proportions selected to selectively precipitate substantially completely said ash-forming impurities while leaving a substantial portion of the asphaltic substances dissolved in said oil, and separating the resulting precipitated impurities from an improved fuel oil.

GERRIT HENDRIK REMAN.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,601,753 Hellthaler Oct. 5, 1926 1,823,558 Burke Sept. 15, 1931 2,176,884 Butz Oct. 24, 1939 2,246,257 Kohn June 1'7, 1941 2,305,248 Fleer et al. Dec. 15, 1942 2,322,083 van der Plas June 15, 1943 2,339,786 Larsen et a1. Jan. 25, 1944 

1. IN A PROCESS FOR THE REFINEMENT OF MINERAL LUBRICATING OILS WHICH CONTAIN IMPURITIES OF THE CHARACTER OF ASPHALTIC SUBSTANCES, WHEREIN THE MINERAL OILS ARE SUBJECTED TO SOLVENT EXTRACTION WITH A SELECTIVE SOLVENT FOR VARIOUS HYDROCARBONS PRESENT THEREIN, THE IMPROVEMENT WHICH COMPRISES PRECEDING SAID SOLVENT EXTRACTION BY TREATING SAID MINERAL OIL CONTAINING THE ASPHALTIC SUBSTANCES WITH A MINOR BUT ASPHALT-PRECIPITATING AMOUNT UP TO ABOUT 10% BY WEIGHT OF ANTIMONY TRICHLORIDE AS SOLE ACTIVE PRECIPITATING AGENT UNDER CONDITIONS TO PRECIPITATE AT LEAST A SUBSTANTIAL PORTION OF SAID IMPURITIES, AND SEPARATING THE RESULTING PRECIPITATED IMPURITIES FROM THE OIL PRIOR TO THE SOLVENT EXTRACTION OPERATION. 